


"I want you to show me what exactly is sex, Human~"

by FanFiction_Writer_3



Category: Undertale (Video Game)
Genre: Anal Sex, Double Penetration, Explicit Sexual Content, Gen, Graphic Description, Lemon, Rough Body Play, Rough Oral Sex, Rough Sex, Sexual Abuse, Tentacle Rape, Vaginal Sex, genderneutral Frisk, genderneutral reader, monster reader, sexual curiosity, uke Frisk
Language: English
Status: Completed
Published: 2018-10-04
Updated: 2018-10-04
Packaged: 2019-07-24 22:08:16
Rating: Explicit
Warnings: Graphic Depictions Of Violence, Rape/Non-Con
Chapters: 1
Words: 3,135
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/16184150
Author URL: https://archiveofourown.org/users/FanFiction_Writer_3/pseuds/FanFiction_Writer_3
Summary: 【Description】Many monsters still never understood the concept of humans, how they function and are very confused toward a majority of what they do and why they do it. You are one of those monsters. You were someone that didn't trust humans, you thought they were retched and had no right being underground where your home is. Until Frisk turned your views around and you two became best friends. After that, slowly you began feeling...strange whenever you were around Frisk; a tingling feeling, a warm sensation filling your lower parts any time you think about Frisk. You tried figuring out what is wrong with you but never got an answer, until finally, you confessed this to the one responsible.





	"I want you to show me what exactly is sex, Human~"

The overwhelmed sensation filled your body just thinking of the thoughts of what you wanted to do to that human. Just seeing them made your lower zone feel all tingly, your soul would just surge in your chest. This has been happening for months now, ever since they came to the monster world and becoming friends, after a battle since at first you thought they were here to wipe all of the monster species away. 

 

This was still all very strange to you, however. It was a need. It was a want. Only this human can get rid of this, and it must be right away.

 

What is it, though? Why is it the human that makes you feel so, hot? When you first met you didn’t even give them a chance to speak before blocking their way from getting any further in Snowdin and yet, now you have the sudden urge to pull them close and make all of your fantasies come to life. Clearly, there is something the human posses to make you so attracted to them, after all, you are not exactly that easy to befriend, and this human managed to do so so easily. 

 

It’s frustrating just to think about. You sighed. You must confront the human about these feelings that have taken control over your body and mind. It’s the right thing, isn’t it? Of course, why would you harbor feelings and not tell the person? Only cowards back away from telling the truth, so what if a majority of the time it is hurtful? It’s the truth dammit. “I am no coward.” You say through gritted teeth. “I must find the human.” Wings suddenly grow out of your back and starting flapping, successfully lifting you up in the air. You flew yourself to your door but once it opened, it revealed the human, Frisk, standing on your porch. They were surprised at first but then smiled seeing you were in fact home. “Oh, hello human.” You brought your feet back to the ground, pulling your wings back into your body. “In what do I bring the pleasure?” Frisk shrugged.

 

“I wanted to come and see you.”

 

“I see. Please, come in.” You shot a tentacle to close the door once Frisk stepped inside, leading them towards the living room. “Would like something to drink? Some tea?” 

 

“Yes, please.” More tentacles shot out and made their way into the kitchen, grabbing two teacups, hot water, and tea bags. As you both continued chatting, the tentacles started pouring the hot water into the cups.   
  
  
“What possessed your mind to want to come and visit my home?”

 

“I just thought we should start hanging out more. Actually, Sans suggested to me once when I was at Grillby’s with him that after lunch I should come over.” A tentacle holding one cup of tea held the drink for Frisk to take. “Thank you.”

 

“Interesting. I was actually going to go out and find you. There is something important I wanted to discuss with you, human.” Frisk tilted their head, blowing lightly at the hot beverage before taking a sip. “Since you’ve come to the underground, there have been these thoughts running through my mind every day. I do not understand what their meaning is but whenever they come, this sensation takes over my body which I cannot understand. The southern zone starts to feel all tingly and just above where, what would be my pelvis, sparks a feeling to which makes me unintentionally squeeze my thighs together.” You take a sip of your own tea, handing it over to one of the tentacles to hold. “I just can’t grasp to what it is I am feeling. It frustrates me very so and I feel as if I am about to break at some kind of point to which I do something which might not be such a good idea to follow through with.” A silence follows after you finished your explanation to the human. You glance at them, noticing the color on their face. It was pink, soon changing to red. “Are you alright, human? Your face is changing color. Are you ill?” Frisk puts down their tea, placing their hands in between their thighs which were pushed together just as you described what has happened to you.

 

“T-that’s a l-l-lot of i-information to t-t-take in...” The color seemed to only darken. 

 

“Yes, it is only right that I shared this with you.” Another silence followed. The tension in the atmosphere was so tense even you were able to identify the human was feeling, uncomfortable. “Human, you are very red. Shall I take you to Alphys for some medicine?” How would they answer? Learning all of these facts about what you have been going through because of them, you just admitted you had a crush on them,  your thoughts about them even being sexual. “I can sense your distress. Do you wish to leave? I understand what I have just told you is strange, unfortunately, I have no other words to explain these feelings I have harvested for you.”

 

Nothing came to mind. No idea how to respond. Doesn’t know what to do next. Frisk wanted to say something, the reason to not responding mostly, is because of the embarrassment they were feeling of how they felt just about the same. Many creatures have crossed Frisk’s path but you were far out one of the most interesting encounters they have made with. 

 

At very first glance Frisk thought you were a human girl that has come into the same situation as them, but upon closer inspection, they noticed wavering in your form. Once in front of you, what they thought was a girl morphed into a large black being, clumps moving around as tentacles sprouted out in attempt to take hold of them. Finally “beating” you in battle, they managed to get you to talk to them and found out that you were, in fact, a shape-shifter, this fact also meaning you had no genitals but still is able to morph yourself into that “gender” even summoning the parts which make it so. Getting to know you after that, was the greatest moments of their life.

 

Their silence was not making it easy for you. They were clearly dealing with something of their own and this was a waste of time of what could have been used to sort out the first problem. “Frisk, do you have anything on your mind you wish to say out loud?” No answer. Oh, this is ridiculous. 

 

But.

 

The state the human is in is very overwhelming. It was making your mind wander to thoughts, thoughts you have been having for a long time. Ooh, the feeling is back. Quickly and suddenly, without putting any thought, you shot your tentacles at the human, wrapping themselves around their torso.

 

“A-ah!” They scream from the action. Another tentacle pushed any objects around you away, slowly inching toward the bounded human. “f-f/-”

 

“This is all just so frustrating.” Now face to face, you take hold of Frisk’s wrist, which you loosed one tentacle around, “Mhm..smells much like cinnamon...just what do you taste like~” You evilly grinned, showing off your sharp teeth. Your tongue slipped between the spacing of your lips to glide along the human’s palm. This was not like you. What was happening? “Delicious~” A tentacle which was holding Frisk slithered it’s way under their sweater, slowly descending it’s way to their chest, wrapping the tip around the nipple.

 

“A-ahhh! N-nooo! nnnghh! Ah! f-f-f/nnn!” 

 

“Your noises are so beautiful, human. It’s making me all bothered.” Frisk was shaking, from the tentacle action and in hope to escape. “I want to hear more~” A different tentacle that was wrapped around Frisk’s leg went up their shorts to rub along their genital.

 

“N-nnhhhn! Ahh ahhh!”

 

“Yess, music to my ears. But...it’s not enough.” With only a snap of your fingers, the tentacles tore off any piece of fabric that was covering the human’s body, sending their cheeks to burn bright red. “I always have found the human body fascinating, but i never got a good look up close. Hehehe, you’ll be my little experiment.” You pulled the human closer to you, watching their mouth widen from each beautiful moaning sound. “Your mouth definitely can open big, hehe. What does  _that_  taste like I wonder~” The moist rough feeling pressed against their cheek made Frisk clench their teeth together, feeling your tongue drag on their skin to their lips. “...looks so soft...so plump.” You shot it between the gap of Frisk’s lips, connecting each others after. The tentacles increased the speed of their movement. Body was hot, sweaty, and shaking from what you were doing. Pleasure was filling Frisk’s body but they couldn’t handle it. Not to mention that they were already starting to drip with cum. 

 

“mnnggff!” Frisk tried fighting back. It was all in vain, however. They couldn’t win against you, you had them tied up. Literally. Soon, too soon, you backed away from the human’s face with a feral grin present on your face.

 

“My, my, human. Your body definitely has an interesting way of reaction to such things. Your heartbeat seemed to have increased in speed and your privates is getting very wet. hehehehe, just what other reactions do you possess~? First, we should remove all of this unwanted fabric to make it easier for me to access your body~” Only a snap of your fingers told the tentacles what to do. Each one took a hold of the human’s article of clothing, tugging all at once and successfully removing them. Embarrassment caught up with Frisk, their bare body open for you to do anything to them as they remained weak and you indifferent from any source of mercy. “A truly beautiful sight.” The tentacles were now only holding Frisk’s wrists and ankles, their wrists held by one while their legs were spread open.  “Your sex organs always were, to me, miraculous of their functions. How about i...” In a swift movement, you had Frisk horizontal to have a better look at their private. Looks so, delicious~

 

“a-ahhhhh aaghhnnn aaah!” You bent down in front of it, first taking a sniff then putting your mouth on it, licking all of it savoring the taste it left in your mouth. “aghhh aahhah aah! s-stooop ahahaahhh!” 

 

“...so good...mhm...ahmmm...i can’t get enough of it. It’s just...mnng ahh...it’s so good~” Each lick added more savor to the interim taste in your mouth. “Oh my, looks like something is dripping. But..ah...it’s just more flavor being added on to the already divine cuisine~” Circular movements your tongue danced against Frisk’s genitalia and you could feel a sudden tension within it. Something in your mind told you to continue what you were doing with your mouth for something will come out of doing so. You were right to follow through. Within only seconds of you eating Frisk out, liquid came out of their private which left a strong bitterness, yet also sweetness, all in your mouth, down to your throat. “Oh my, what a very unusual thing to come out of someone. I do not believe I ever heard about this, very much tasty substance. Tell me human, what is this?”

 

Frisk very weakly lifted up their head to you. “n-ngnn...s-stop...th-this...i-i-ahhg...”

 

“Tch. You are making this very hard for me, human. Forgetting that, I want to know what other sounds you can make. From what I’ve already heard so far, I can conclude that it is a continuation of, what you would call a groan and moan, but it has a more of pleasurable reaction from something acting towards your body. Oh, hnhnhn, is what I’m doing, pleasurable, human~?”

 

“Y-you’re si-ahhnn...s-sick!”   
  


“I am only curious, there is no need for calling out such rude assumptions.” From the tension growing in your body the tentacles gripping Frisk’s limbs tightened causing yelp to slip through Frisk’s lips. 

 

“A-ah!” Another large chesire grin stretched on your face getting another idea of how to make this human react in an amusing way but also out of curiosity. 

 

“I now just realized the structure of a human body is very different compared to the monsters down here in the underground~” A tentacle was placed onto Frisk’s collarbone. “You have more body parts, less than others. You have various orifices, and it just so happens I have the right amount of, ‘objects’, to fill those your body holds~” The tentacle slithered down to the first hole, a second going to their anus, and third going up to their mouth.

 

“W-what are y-you doi-AAAGHHH! AAHH! AHH! HNNN-MMMNNPHHFF GHHFF!” All at once the tentacles filled the orifices they were brought to. Pain was all Frisk could feel from the unusual feeling of having objects inside of their body, violently moving back and forth, each a different pace. “NGFFHHH! NHNNGUGHHFFFNNGHHH! GHHHHNNNGGGFFFFMPPHH!” You wanted pleasure to subdue Frisk’s body in the interest of what other verbal and physical reactions will come out of it, however, there weren’t any changes from their previous. 

 

Frustrated, you clicked your teeth. “Is this all you can do? I’m disappointed. Humans are supposed to have multiple reactions towards specific scenario’s of situations but so far its been the same. Maybe I was wro-huh? Hohoho, what is this that catches my eye~?” Strange liquid-like substance starts leaking out of the human’s privates. Could it be from..." Swiftly, with no hesitation, the tentacle which was thrusting in and out of their private ripped out, causing a loud muffled shriek to bubble up in Frisk’s throat. With nothing restricting its pathway, the substance started spilling out faster. A streak of it dripped onto one of your fingers. You brought it to your mouth, slowly sucking it and swallowing. “It’s what I tasted when I was feasting on your strange body part, but it’s, sweeter. More, flavor-filled.” Eyes trailed up Frisk’s body, their eyes shut tightly with heavy tears streaming down their hallowed red cheeks as their and arms violently shook, back arched. "This...image I am seeing..." The bottom half of your body rippled. "It's giving me such euphoria. The look of submission and defeat on your face - in your eyes~" The rippling continued, seemingly to move faster. "I'm feeling something I never felt before...Human, what is going on with me?! S-something is forming on me!" You became more historical as your substance turned into something long, a white material dripping out of the tip. Finally, the tentacles in Frisk's orifices retracted back into your body but the others still restrained their arms and legs. Frisk harshly wheezed and coughed, tears thickly rushing down their cheeks. They shakily brought up their head and the moment they saw what had just formed on your body, their eyes widened.   
  
  
"N-no...NO!"  
  
  
"Human..seeing the after picture of your privates...compared to your before it looks so..." You reached a finger out to touch the clenching heat. "It must be because of this that this object appeared. I must put this inside you."  
  
  
"NO! STO-OP! P-PLEASE!" Frisk thrashed in their restraints. You walked closer to them with your newly formed penis being held in your palm. The tip grazed against the entrance making Frisk grit their teeth and throw their head back. "NO DON'T!" Their voice started cracking from screaming.  
  
  
"Now, now, you must cooperate, human. I just want to feel what it is like to be inside another~" You pushed the entire length inside of Frisk, their walls instantly clenching around it.   
  
  
"AAAHHH AAHH AAH AAAAH! NGAHAAAAHHH AAAH!" You curiously moved your hips forward to see if that would make any effectiveness happen. "NGAHAAAAAAAHHHHAAAGHH!" Apparently, it did. "AGHHAAH AAHHH AAH! AAHH GAHAAHHHAH!"  
  
  
"S-so by thrusting m-my hips b-back and f-f-for - I-I can't concentrate! Inside of you is so hot and tight, it is shooting pleasure through me! H-Human, you are an i-intriguing specimen! Ngh, I just can't stop moving."  
  
  
"S-STOP PLE-EASE! AGHHAAAHHHAHAHH! N-NO MORE!" The human continued to beg but you wouldn't listen. The amount of elation you were experiencing was far greater than anything else you ever felt. Your movements became faster in speed and rougher in thrusts. "NGAHAAAAAAHH STOP! ST-STOP!" Jam after jam, you were never ending with the action. Something was building up, you could feel it. And it was about to come out of you.   
  
  
"Wh-what is this? Ahghaah! I-I feel like something is going to come out of me!"   
  
  
"N-NO! F/N D-DON'T!"  
  
  
"I can't control i-it! I-it's coming!"   
  
  
"N-NO AGHHHHAAAAGHHAAAH!" The white cum ejaculated from your penis and into any empty space inside of Frisk. They let out groans from feeling it against their walls and even drip from out from around your genital for about a minute until it eventually stopped. Low breaths were what you exhaled and inhaled when you finally stopped, feeling your energy decreasing by the second. You slid out of Frisk and watched your cum slowly gush out of their body in large amounts. "Ghaaghgh...nghh.." Even if they wanted to, Frisk couldn't let out anymore more cries or screams due to the amount they already did for long terms of time.   
  
  
"I understand why one would be so intoxicated by having these pleasures. The exhilarated feeling from doing this, it is so addicting. Do you humans also take part in this? Do they all scream and cry as you did? Please human, tell me what you know of all of this~" Your excitedly clapped your hands together and grinned a toothy smile. Frisk couldn't even keep their head up but by the looks of them - saliva was drooling out of their wide-opened mouth, their eyes were narrowed and filled with tears, and their chest was heaving up and down erratically - you concluded they were also low on energy. "Hmm, perhaps this has tired you out exceptionally. Would you like to rest for a while?" Frisk couldn't speak. "I shall bring you upstairs. I apologize for ripping your clothing, I felt compelled to. While you rest I will try to fix them." You moved the tentacles so the human was in front of you in a horizontal position so you could hold them with one arm under their back and the other under their legs. "Do not worry human, for now, I am pleased with the information I gathered. However, soon I will need your assistance again." Frisk wanted to fight back but they were too weak from previously fighting back.   
  
  
They never thought you'd ever do such a thing, thought that you were capable of this. Frisk regretted coming to your house, and they have no idea how they will around you after all of this.


End file.
